1. Technical Field
The present invention relates to liquid crystal display devices and display methods for displaying images by stacking a plurality of liquid crystal panels.
2. Description of Related Art
With the recent advancement of so-called “information-aligned society”, electronic equipment, typified by personal computers, PDA (Personal Digital Assistants) and the like, is now being widely used. Due to the widespread use of such electronic equipment, the demand for portable electronic equipment usable in offices and outdoors has been created, and the reduction in size and weight thereof has been desired. As a means for achieving such objects, liquid crystal display devices are widely used. Liquid crystal display devices represent the indispensable technique for realizing the reduction in power consumption of battery-driven portable electronic equipment, as well as for merely realizing the reduction in size and weight thereof.
Liquid crystal display devices are roughly classified into a reflective liquid crystal display device and a transmissive liquid crystal display device. The reflective liquid crystal display device is designed so that light beam to be incident from a front face of a liquid crystal panel is reflected by a rear face of the liquid crystal panel, and an image is visually identified by the reflected light, while the transmissive liquid crystal display device is designed so that an image is visually identified by a transmitted light from a light source (i.e., backlight) provided at a rear face of a liquid crystal panel. The reflective liquid crystal display device is inferior in visibility since an amount of the reflected light is inconstant depending on environmental conditions; therefore, in particular, as a display device for a personal computer or the like which performs multi-color or full-color display, a transmissive color liquid crystal display device, which uses color filters, is commonly utilized.
As the color liquid crystal display device, an active-driven-type liquid crystal display device that uses a switching element such as a TFT (Thin Film Transistor) is widely utilized at present. Although this TFT-driven liquid crystal display device has a high display quality, the light transmittance of a liquid crystal panel is as low as about several percent under the status quo, and therefore, a high brightness backlight is required in order to obtain high screen brightness. Thus, the power consumption caused by the backlight is unfavorably increased. Furthermore, since the color display that uses color filters is performed, each pixel has to be composed of three sub-pixels, thus making it difficult to realize high resolution and making the display color purity insufficient.
In order to solve such problems, the present inventors have developed a field sequential liquid crystal display device (see, for example, Non-Patent Documents 1, 2, and 3). This field sequential liquid crystal display device does not need any sub-pixels unlike a color filter liquid crystal display device, and is thus capable of realizing higher resolution display with ease and utilizing the color of light emitted from a light source as it is without using any color filters, resulting in high display color purity. Moreover, the light use efficiency is also high, which further achieves an advantage that the power consumption is low. However, in order to realize the field sequential liquid crystal display device, the fast response of liquid crystal (2 ms or less) is absolutely necessary.
Therefore, in a quest to achieve the fast response of the field sequential liquid crystal display device having the excellent advantages as described above, the present inventors have conducted research and development on the driving of liquid crystal, such as ferroelectric liquid crystal having spontaneous polarization which can be expected to exhibit a response 100 to 1000 times faster than ever before, by a switching element such as a TFT (see, for example, Patent Document 1). In ferroelectric liquid crystal, the longitudinal axial direction of liquid crystal molecules aligned in parallel with a glass substrate is tilted by voltage application. A liquid crystal panel containing ferroelectric liquid crystal therein is sandwiched between two polarizers whose polarizing axes are orthogonal to each other, and the double refraction caused by a change in the longitudinal axial direction of liquid crystal molecules is utilized to change the intensity of transmitted light.
Actually, in recent years, the need for three-dimensional image display has also been intensified, and a liquid crystal display device for displaying a three-dimensional image by stacking a plurality of liquid crystal panels has been proposed (see, for example, Non-Patent Document 4).
[Patent Document 1] Japanese Patent Application Laid-Open No. 11-119189
[Non-Patent Document 1] T. Yoshihara et al., ILCC 98, P1-074, published in 1998
[Non-Patent Document 2] T. Yoshihara et al., AM-LCD '99 Digest of Technical Papers, p. 185, published in 1999
[Non-Patent Document 3] T. Yoshihara et al., SID '00 Digest of Technical Papers, p. 1176, published in 2000
[Non-Patent Document 4] M. Date et al., IDW '03 Proceedings of The 10th International Display Workshops, p. 1409, published in 2003